Receptor elements for use in non-impact printing by electrostatographic methods, using toner particles, especially, but not exclusively, dry toner particles (i.e. electrophotography, ionography, direct electrostatic printing, magnetography) are well known in the art. Typically hydrophobic image receiving layers have been described: e.g. polyamides in U.S. Pat. No. 3,535,112, vinylidene chloride copolymers in U.S. Pat. No. 3,539,340.
In e.g. U.S. Pat. No. 4,320,186 the use of acrylic polymers in toner receiving layers is disclosed. In that disclosure it is taught to coat the polymeric layer from a coating solution with toluene as solvent.
In EP-A-104 074 a receiving layer for toner particles comprising a polymethylmethacrylate resin and being coated from a solution containing methyl ethyl ketone and toluene is disclosed. In U.S. Pat. No. 4,415,626 it is disclosed to use an image receiving layer comprising a film forming binder as e.g. poly(vinylalcohl) or cellulose derivatives, and hardening said binder.
In U.S. Pat. No. 4,621,009 an image receiving layer comprising a polyester resin as binder resin is disclosed, the polyester being coated from a coating solution in methyl ethyl ketone and toluene.
In EP-A-240 147 a toner receiving layer comprising polymethylmethacrylate as binder is disclosed. Again this binder is coated from a solution in methyl ethyl ketone and toluene.
For imaging materials to be used for non-impact printing with electrostatographic methods using dry toner particles, it has been disclosed to use image receiving layers comprising resins being adapted to the toner particles. In e.g. EP-A-349 227 it is disclosed to coat a toner receiving layer comprising a polyester predominantly having terephthalic acid moieties and bisphenol-A moieties on a polyester support for receiving toner particles having as toner resin a polyester with predominantly fumaric acid moieties and bisphenol-A moieties. The advantage is that the binder of the image receiving layer has good compatibility with the toner resin and has a larger elasticity than the toner resin. When used as an image receiving layer for making transparencies for overhead projection with dry toner particles, this provides a smooth fixed image with sharp edges and no scattering of light occurs, giving a clear projected image. Again the toner receiving layer is coated from a volatile organic solvent.
In U.S. Pat. No. 5,208,093 it is disclosed to provide a toner receiving layer on a support wherein the toner receiving layer contains a polymer with equal or lower storage elasticity modulus than the toner resin. Again the image receiving layer is coated from a solution in organic solvents.
As stated above, many image receiving layers for dry toner particles are coated from an organic solvent, which is nowadays undesirable, both from the view point of safety in the workplace and of environmental concerns.
Therefore layers comprising a resin that can be coated from an aqueous medium are very desirable and such layers have been disclosed.
In U.S. Pat. No. 4,168,338 a toner receiving layer comprising an acrylic polymer with a carboxyl group content between 2 and 30% by weight and an epoxy resin has been disclosed.
In U.S. Pat. No. 4,245,025 a toner receiving sheet is disclosed comprising on a paper support a layer consisting essentially of a thermoplastic acrylic-styrene copolymer with acid value between 10 and 170 and hydrophobic silica.
In EP-A-613 056 a toner receiving layer coated from an aqueous dispersion has been disclosed and the binder of the toner receiving layer is a cross-linked urea-formaldehyde resin powder. Image receiving layers, well suited for ink-jet printing and comprising polymeric latices together with other polymeric compounds have been disclosed in e.g. U.S. Pat. No. 5,624,743.
The toner receiving layers-containing polymeric latices seem to have a rather complicated structure and constitution, therefore further toner receiving layers that can be produced via aqueous coating solution, especially when coated on a plastic substrate, are still desirable.